Question

Is there a difference between a homogeneous mixture of hydrogen and oxygen in a 2: 1 ratio and a sample of water vapor? Explain.

Short answer

Yes, there is a difference between a homogeneous mixture of hydrogen and oxygen in a 2:1 ratio and a sample of water vapor. The homogeneous mixture consists of individual hydrogen (H2) and oxygen (O2) gas molecules, with no chemical bonding between them. In contrast, water vapor consists of chemically bonded H2O molecules, which exhibit different chemical properties and reactivities than the separated hydrogen and oxygen gases in the mixture.

Step-by-step solution

Understand the components of a homogeneous mixture

In a homogeneous mixture, the components are uniformly distributed and appear as a single phase. In this case, we have hydrogen and oxygen gases mixed in a 2:1 ratio. Hydrogen has the chemical formula H2, while oxygen is O2. These are not chemically bonded, but merely mixed together.

Understand the composition of a sample of water vapor

Water vapor is formed when water, a compound with the chemical formula H2O, evaporates. This compound consists of two hydrogen atoms bonded to one oxygen atom. Water vapor is a gas with the same chemical composition as liquid water, but in the gaseous state.

Compare the bonding in both cases

In the homogeneous mixture of hydrogen and oxygen, there is no chemical bonding occurring between the hydrogen and oxygen gas molecules. They remain separate as individual molecules of H2 and O2. However, in a sample of water vapor, the hydrogen atoms and the oxygen atoms are chemically bonded, forming H2O molecules.

Compare the chemical properties of both cases

Both the homogeneous mixture of hydrogen and oxygen and the water vapor are in the gas phase. The homogeneous mixture of hydrogen and oxygen retains the properties of hydrogen and oxygen separately and can be reactive under certain conditions (e.g., if ignited, it could lead to an explosion). On the other hand, water vapor has distinct physical and chemical properties, such as boiling and melting points, and is less reactive than the individual hydrogen and oxygen gases.

Conclude the difference between both cases

Yes, there is a difference between a homogeneous mixture of hydrogen and oxygen in a 2:1 ratio and a sample of water vapor. The homogeneous mixture consists of individual hydrogen and oxygen gas molecules, whereas water vapor consists of chemically bonded H2O molecules. These have different chemical properties and reactivities.

Key concepts

Homogeneous Mixture

A homogeneous mixture is a type of mixture in which the components are evenly distributed, resulting in a uniform composition throughout. In the case of hydrogen and oxygen gases mixed in a 2:1 ratio, this mixture remains homogeneous because you cannot see the separate gas components. They distribute uniformly throughout the container. The molecules do not react with each other or form new chemical bonds. Rather, they coexist in the same space. These mixtures are often referred to as solutions, especially when discussing solutions in liquid form.
The most important characteristic of a homogeneous mixture is that it appears to be a single phase, whether it's a solid, liquid, or gas. This is why a solution like saltwater looks just like pure water, even though it contains dissolved salt particles.

Water Vapor

When we talk about water vapor, we're referring to water in its gaseous state. Water vapor forms when liquid water evaporates, which means the water molecules have enough energy to break free from their liquid bonds and rise into the air as gas. This process does not alter the chemical structure of the water itself – the water molecules remain as H2O.
The nature of water gaseous at different temperature levels allows it to perform differently in various conditions. It's still the same chemical compound but behaves differently physically as it transitions from liquid to gas. Importantly, water vapor should not be confused with steam, which is actually a mist of tiny liquid water droplets.

Chemical Properties

Chemical properties are the characteristics that describe a substance's potential to undergo chemical changes or reactions under specific conditions. In the context of a homogeneous mixture of hydrogen and oxygen, each of these gases retains its individual chemical properties.
For example, hydrogen is highly flammable and can produce a lot of heat when it reacts with oxygen. Oxygen is essential for combustion. However, when these two gases are merely mixed, they do not create any chemical bond, thus both retain their reactive properties separately.
On the other hand, in water vapor, the hydrogen and oxygen are chemically bonded as water. This bonding significantly alters their original reactive properties, making water vapor less reactive compared to either hydrogen or oxygen gas. Water vapor acts differently due to its specific molecular structure separated from the independent properties displayed by its initial elements.

Molecular Composition

Molecular composition refers to the types of atoms present in a substance and their arrangement. In the homogeneous mixture of hydrogen and oxygen, the molecular composition consists of separate H2 and O2 molecules. Each type of molecule retains its own identity without forming any new compounds.
Conversely, in water vapor, the molecular composition is different; it consists of H2O molecules. In these molecules, two hydrogen atoms are chemically bonded to one oxygen atom. This bond formation results in a stable, distinct compound with chemical properties different from the separate gases.
Understanding molecular composition helps explain the varying behaviors and properties of substances, especially when comparing mixtures like hydrogen and oxygen with compounds like water vapor. Each composition leads to unique characteristics that define chemical reactions and interactions.